Optical visualization of MoS2 grain boundaries by gold deposition

Abstract

The grain boundaries (GBs) in continuous films or domains of MoS2 are vital to its optical and electrical properties. Almost all previous approaches for GBs visualization are based on microscopy and spectroscopy and only effective for domains with less than several micrometers in size. Here we report a simple method for the visualization of large GBs in MoS2 surface by optical microscope. Gold was deposited on the MoS2 grown by chemical vapor deposition, and then the GBs could be observed by optical microscope. Upon gold deposition on MoS2, the entire GBs of large-area MoS2 were clearly visualized using this method. To verify the result, the GBs were also characterized via scanning electron microscopy, transmission electron microscopy and atomic force microscopy. It showed the small particles of gold were clustered together on GBs, which had a larger binding energy than the inner regions. The method is universal and allows for the nondestructive identification of the GBs in any two dimensional materials with large area.

Keywords

grain boundaries gold deposition optical microscope single layer MoS2

Lulu Sun is now a master candidate at the School of Materials Science and Engineering, Qingdao University of Science & Technology. She is jointly supervised by Prof. Jian Zheng at the Institute of Chemistry, Chinese Academy of Sciences. Her research focuses on the synthesis and characterization of 2D materials.

Jian Zheng received his PhD degree in 2011 from the Institute of Chemistry, Chinese Academy of Sciences. Then he worked as a Postdoc at National University of Singapore (2011–2015). Now he is a professor at the Institute of Chemistry Chinese Academy of Sciences. His current researches focus on the growth and characterization of 2D materials, and their applications in nano-electronics.